If you read the original part of this thread that I started back in Februar=
y (http://tech.groups.yahoo.com/group/naturerecordists/message/46737), you'=
ll see that I had similar problem, even though I went to a branch of the sa=
me rubber specialist that Vicki bought her foam from.=0D
=0D
Different branches of the same store were recommending different things. Vi=
cki's store had grey high density open cell foam, but mine said that stuff,=
which they called acoustic foam, only came in thin sheets. They offered so=
mething coloured that felt similar, but which they insisted wasn't acoustic=
foam, so I was dubious about using it.=0D
=0D
I happened to spot a piece of what looked like thick acoustic foam in their=
offcuts bin, and bought that instead. They had no idea where it came from,=
so if I want more then I'll have to go through the same process again.=0D
=0D
It would be good if someone could come up with an objective test for identi=
fying this stuff. I was told I should be able to blow through it, but with =
more difficulty than with medium density foam, which I wouldn't call an obj=
ective test unless I had several samples to compare.=0D
=0D
I wonder if it would help if you asked your supplier for the contact detail=
s of the distributor or manufacturer. Surely they will know.=0D
=0D
Peter Shute=0D
=0D
=0D
--------------------------=0D
Sent using BlackBerry=0D
=0D
________________________________=0D
From: =0D
To: =0D
Sent: Thu Jul 12 02:08:21 2012=0D
Subject: [Nature Recordists] Re: Foam for SASS=0D
=0D
=0D
=0D
Hi Vicki,=0D
=0D
The foam I am able to find locally is green (whatever that means!). It is c=
alled high-density foam (they also sell "regular" density, which is white),=
and although the clerks in the store had no idea about open or closed cell=
, it is absorbent like a sponge, so I guess it is open-cell. It isn't nearl=
y as dense as I expected, less so, I think, than the foam mattress pad I me=
ntioned. It is quite squishy. The 4" x 6" x 9" scrap I bought weighs 125 gr=
ams.=0D
=0D
Could I possibly have the right thing? I can return it if I bought the wron=
g material, but how can I tell? Does anyone know?=0D
=0D
Many thanks,=0D
=0D
John Crockett=0D
Westminster, Vermont=0D
=0D
--- In <naturerecordists%40yahoogrou=
ps.com>, vickipowys <> wrote:=0D
>=0D
> Hi John (& John),=0D
>=0D
> I looked at your link John C, all the foam they make seems to be=0D
> white. I recall Rob Danielson found a US source that had 'High=0D
> Density Open-cell Foam' that was dark grey in colour, the colour was=0D
> the way of identifying the type of foam i.e. different colours for=0D
> different types of foam. You should not need to buy a whole sheet of=0D
> it, there must be a foam place that will custom cut it. At one time=0D
> Rob was sending out blocks of grey foam to anyone who wanted it.=0D
>=0D
> The foam you are after should not be at all heavy, I note that some=0D
> of the more dense foams are actually quite heavy.=0D
>=0D
> I agree with everything John H has said about the claims made by=0D
> Crown, I don't think anyone really quite knows what goes on. But it=0D
> is logical that high frequency sounds would be more easily blocked by=0D
> the foam, than would low frequency sounds.=0D
>=0D
> Don't forget that the (metal) wrap around the foam also blocks=0D
> sound. The original Crown was made of plastic but the blocking=0D
> effect would be the same.=0D
>=0D
> Vicki Powys=0D
> Australia=0D
>=0D
>=0D
>=0D
>=0D
> On 10/07/2012, at 5:07 AM, hartogj wrote:=0D
>=0D
> > Hi John=0D
> >=0D
> > Yes, it has been discussed before on this list, but before you=0D
> > search the archives have a look at Rob Danielson's boundary mic=0D
> > blog at:=0D
> > http://diystereoboundarymics.blogspot.com/=0D
> >=0D
> > I seem to recall a Crown description of the SASS saying that the=0D
> > low frequencies pass around the array and through the nose in a way=0D
> > that sum thus boosting the low end a bit. This balances those lower=0D
> > frequencies with the higher frequencies that are amplified by the=0D
> > boundary plates, and provides a flatter overall frequency=0D
> > response. Disclaimer: I am probably not remembering that=0D
> > accurately, and even if I am, it may have just been Crown marketing=0D
> > hype.=0D
> >=0D
> > John Hartog=0D
> > rockscallop.org=0D
> >=0D
> >=0D
> > --- In <naturerecordists%40yahoo=
groups.com>, "John Crockett"=0D
> > <jladd@> wrote:=0D
> >>=0D
> >> Hi Vicki=0D
> >>=0D
> >> That's interesting, and surprising. I, too, expected the nose foam=0D
> >> to be more dense. I am currently using about a 4cm thick piece of=0D
> >> the #1 foam on top of the mic capsules as a wind baffle, and it=0D
> >> seems to be pretty much acoustically transparent. Is the nose=0D
> >> baffle only attenuating some frequencies, or none at all? Is it=0D
> >> thick enough that it separates the channels even though it is=0D
> >> fairly transparent?=0D
> >>=0D
> >> I guess what I am using in my prototype (my foam #4) is probably=0D
> >> low or medium density closed cell foam. I guess, but I don't know!=0D
> >> It is not absorbent, it is fairly but not extremely rigid, and the=0D
> >> cells are large. Lots of air space, but the plastic cell walls are=0D
> >> fairly rigid. And I added some cardboard around that to create=0D
> >> even more separation between the two channels. I rather like the=0D
> >> image it produces (airplane noise aside), which is what matters in=0D
> >> the end, but it sounds like that is not the intent of the Crown=0D
> >> SASS. What is the theory? What is acoustically separating those=0D
> >> two omni capsules?=0D
> >>=0D
> >> If this has all been explained in detail somewhere, can you=0D
> >> provide a link to that discussion?=0D
> >>=0D
> >> Unfortunately I am not aware of any foam supply stores anywhere in=0D
> >> New England. I've tried searching online and I'm just not sure=0D
> >> what I am looking for. This is the sort of thing I find online:=0D
> >>=0D
> >> http://www.onlinefabricstore.net/specialty-stores/automotive-store/=0D
> >> automotive-upholstery-padding-and-supplies/automotive-upholstery-=0D
> >> foam/open-cell-foam/high-density-open-cell-foam.htm?N=3D11774=0D
> >> +4294963398=0D
> >>=0D
> >> This looks a lot like my foam #2 - the mattress foam, but it's=0D
> >> hard to tell looking at pictures online. Is this what I want?=0D
> >>=0D
> >> I wish someone could send me a tiny sample of the right stuff so I=0D
> >> know what it looks and feels like. Then I could go to a fabric and=0D
> >> upholstery store and see if they have it. Please contact me off=0D
> >> list if that is possible! I'll pay postage!=0D
> >>=0D
> >> Many thanks! (Sorry for all the exclamation marks but I am truly=0D
> >> grateful to everyone who contributes to this fascinating and=0D
> >> informative group).=0D
> >>=0D
> >> John=0D
> >>=0D
> >> --- In <naturerecordists%40yaho=
ogroups.com>, vickipowys <vickipowys@>=0D
> >> wrote:=0D
> >>>=0D
> >>> John,=0D
> >>>=0D
> >>> You would need to go to a foam supply store, rather than a building=
=0D
> >>> store. In Australia we have Clark Rubber chain stores who=0D
> >>> specialize=0D
> >>> in foam, not sure who does in US.=0D
> >>>=0D
> >>> You can tell if it is open cell if the foam absorbs water like a=0D
> >>> sponge.=0D
> >>>=0D
> >>> The idea in the original SASS design is that some sound can pass=0D
> >>> through the open-cell foam. However I know of several people=0D
> >>> who, in=0D
> >>> misunderstanding the SASS design, have built the front 'nose' out of=
=0D
> >>> something solid e.g. closed cell foam or balsa-wood. And the sounds=
=0D
> >>> samples I have heard are just great, so perhaps it does not matter=0D
> >>> hugely.=0D
> >>>=0D
> >>> I would say that your number 1) would be most like the open-cell=0D
> >>> foam=0D
> >>> used for the nose of the original SASS.=0D
> >>>=0D
> >>>=0D
> >>> Vicki Powys=0D
> >>> Australia=0D
> >>>=0D
> >>>=0D
> >>>=0D
> >>> On 09/07/2012, at 7:01 AM, John Crockett wrote:=0D
> >>>=0D
> >>>> If I can re-open this thread,=0D
> >>>>=0D
> >>>> I'm still unclear about exactly what high-density open-cell foam=0D
> >>>> is. My local building supply store hasn't a clue.=0D
> >>>>=0D
> >>>> I have several types of foam lying around the house.=0D
> >>>>=0D
> >>>> 1) One is very soft and pliable, like the foam windscreens that=0D
> >>>> come with most microphones. It came as packing material.=0D
> >>>>=0D
> >>>> 2) Another is a bit denser and thicker, the sort of foam that is=0D
> >>>> used for mattresses.=0D
> >>>>=0D
> >>>> 3) Then we have what in the USA is called blue board. This is a=0D
> >>>> very dense, small cell, rigid foam that comes in sheets of various=
=0D
> >>>> thicknesses and is used for building insulation (we have some left=
=0D
> >>>> over from insulating our cellar). Sort of similar to styrofoam.=0D
> >>>>=0D
> >>>> 4) Finally I have sort of an odd thing that came as cushioning=0D
> >>>> material in a box with an electronic device. It is rigid, like the=
=0D
> >>>> blue board, but the cells are much larger than that in the blue=0D
> >>>> board and therefore it is a bit springy when pressed. It is not as=
=0D
> >>>> rigid as styrofoam.=0D
> >>>>=0D
> >>>> 5) Oh, and somewhere I have a block of stiff, small-celled foam=0D
> >>>> that is used to go between a kayak or canoe and the roof of the=0D
> >>>> car.=0D
> >>>>=0D
> >>>> Are any of these "high-density, open-cell" foam? If not, what does=
=0D
> >>>> this creature look and feel like?=0D
> >>>>=0D
> >>>> I built a prototype sass array using EM172 capsules, and #4 above=0D
> >>>> for the nose baffle, and it works well as far as I can tell, but=0D
> >>>> for the real thing (built for AT3032 mics), I'd like to get it=0D
> >>>> right.=0D
> >>>>=0D
> >>>> Many thanks!=0D
> >>>>=0D
> >>>> John=0D
> >>>>=0D
> >>>> John Crockett=0D
> >>>> Westminster, Vermont=0D
> >>>>=0D
> >>>> --- In <naturerecordists%40ya=
hoogroups.com>, Peter Shute <pshute@>=0D
> >>>> wrote:=0D
> >>>>>=0D
> >>>>> I made it to Clark Rubber tonight, and sure enough it wasn't as I=
=0D
> >>>>> expected. According to this store, high density foam comes in=0D
> >>>>> colours, and acoustic foam is grey and only 2" thick.=0D
> >>>>>=0D
> >>>>> Then I spotted a light grey scrap in a bin, exactly the size I=0D
> >>>>> wanted, but twice as long. It felt like the acoustic foam, so I=0D
> >>>>> think it's the right stuff. They weren't sure what it was and=0D
> >>>>> thought a customer had left it behind after bringing a piece in=0D
> >>>>> for cutting, and let me have it for $3.=0D
> >>>>>=0D
> >>>>> There's something a bit disturbing about an industry that's=0D
> >>>>> inconsistent about what it calls its products.=0D
> >>>>>=0D
> >>>>> Peter Shute=0D
> >>>>>=0D
> >>>>>=0D
> >>>>> --------------------------=0D
> >>>>> Sent using BlackBerry=0D
> >>>>>=0D
> >>>>> ________________________________=0D
> >>>>> From: <naturerecordists%40ya=
hoogroups.com>=0D
> >>>>> To: <naturerecordists%40yaho=
ogroups.com>=0D
> >>>>> Sent: Tue Feb 28 10:17:03 2012=0D
> >>>>> Subject: Re: [Nature Recordists] Re: Foam for SASS=0D
> >>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>> Peter,=0D
> >>>>>=0D
> >>>>> re filling inside of SASS box - well I've overcome that problem by=
=0D
> >>>>> making my SASSes out of solid blocks of closed-cell foam (it's=0D
> >>>>> lighter weight too) - see my website. If you've made a wooden SASS=
=0D
> >>>>> you could fill the gap with closed cell foam.=0D
> >>>>>=0D
> >>>>> Vicki=0D
> >>>>>=0D
> >>>>> On 28/02/2012, at 9:08 AM, Peter Shute wrote:=0D
> >>>>>=0D
> >>>>>> Excellent, if I can tell by colour then they can't trick me. It=0D
> >>>>>> sounds pretty cheap, so I'll get enough for future experiments.=0D
> >>>>>>=0D
> >>>>>> Can you recommend what to fill the inside of the box with?=0D
> >>>>>>=0D
> >>>>>> Peter Shute=0D
> >>>>>> ________________________________=0D
> >>>>>> From: <naturerecordists%40y=
ahoogroups.com><naturerecordists%=0D
> >>>>>> 40yahoogroups.com>=0D
> >>>>>> <naturerecordists%4=
Message: 0yahoogroups.
Subject: com><naturerecordists%=0D
> >>>>>> 40yahoogroups.com>] On Behalf Of vickipowys=0D
> >>>>>> Sent: Tuesday, 28 February 2012 8:54 AM=0D
> >>>>>> To: <naturerecordists%40yah=
oogroups.com><naturerecordists%=0D
> >>>>>> 40yahoogroups.com>=0D
> >>>>>> Subject: Re: [Nature Recordists] Re: Foam for SASS=0D
> >>>>>>=0D
> >>>>>>=0D
> >>>>>>=0D
> >>>>>> Yes Peter, Clark Rubber call their stuff 'high density foam'=0D
> >>>>>> and it=0D
> >>>>>> is grey in colour (as opposed to medium density foam which=0D
> >>>>>> comes in=0D
> >>>>>> many colours). The acoustic foam is black. My nearest Clarks used=
=0D
> >>>>>> to be at Bathurst (2 hours away) but they closed and now I=0D
> >>>>>> have to=0D
> >>>>>> get it via mail order from Dubbo where they can never cut it=0D
> >>>>>> straight. I agree Clark's website is pretty useless. If you=0D
> >>>>>> can get=0D
> >>>>>> Clarks to cut it in blocks around the size you want, you can then=
=0D
> >>>>>> taper the sides according to Rob's specifications, using a razor=
=0D
> >>>>>> knife with a new blade extended all the way out. And tidy up=0D
> >>>>>> the cut=0D
> >>>>>> surfaces with a little piece of fine sandpaper.=0D
> >>>>>>=0D
> >>>>>> Vicki=0D
> >>>>>>=0D
> >>>>>> On 28/02/2012, at 8:17 AM, Peter Shute wrote:=0D
> >>>>>>=0D
> >>>>>>> Thanks, Vicki. You mean the one they're calling high density but=
=0D
> >>>>>>> which isn't acoustic foam? If that works then it would be better=
=0D
> >>>>>>> not to have to glue it.=0D
> >>>>>>>=0D
> >>>>>>> It's a pity I can't see the stuff on their web site before I go=
=0D
> >>>>>>> there, or even just order it online to save myself the=0D
> >>>>>>> trouble, but=0D
> >>>>>>> the web site is a mess. A search for high density foam takes=0D
> >>>>>>> me to=0D
> >>>>>>> anything but what I expect to see.=0D
> >>>>>>>=0D
> >>>>>>> Peter Shute=0D
> >>>>>>>=0D
> >>>>>>> ________________________________=0D
> >>>>>>> From: <naturerecordists%40=
yahoogroups.com><naturerecordists%=0D
> >>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>> 40yahoogroups.com>=0D
> >>>>>>> <naturerecordists%=
Message: 40yahoogroups.
Subject: com><naturerecordists=0D
> >>>>>>> %=0D
> >>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>> 40yahoogroups.com>] On Behalf Of vickipowys=0D
> >>>>>>> Sent: Tuesday, 28 February 2012 8:06 AM=0D
> >>>>>>> To: <naturerecordists%40ya=
hoogroups.com><naturerecordists%=0D
> >>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>> 40yahoogroups.com>=0D
> >>>>>>> Subject: Re: [Nature Recordists] Re: Foam for SASS=0D
> >>>>>>>=0D
> >>>>>>>=0D
> >>>>>>>=0D
> >>>>>>> Peter,=0D
> >>>>>>>=0D
> >>>>>>> I have always used the grey high-density foam from Clark Rubber,=
=0D
> >>>>>>> which is fairly close in texture to the original foam that=0D
> >>>>>>> was used=0D
> >>>>>>> in the Crown SASS design. And you won't have to glue either.=0D
> >>>>>>>=0D
> >>>>>>> Vicki=0D
> >>>>>>>=0D
> >>>>>>> On 28/02/2012, at 7:28 AM, Peter Shute wrote:=0D
> >>>>>>>=0D
> >>>>>>>> Good enough for me then. I'll try to get there tonight and get=
=0D
> >>>>>>>> some=0D
> >>>>>>>> of the acoustic foam.=0D
> >>>>>>>>=0D
> >>>>>>>> The plans also say to fill the void with "dense absorptive=0D
> >>>>>>>> material=0D
> >>>>>>>> like rubber backed carpet padding". Does that mean similar=0D
> >>>>>>>> material=0D
> >>>>>>>> to that used for the baffle? I.e. can I just get a bit more=0D
> >>>>>>>> of it=0D
> >>>>>>>> to put in there?=0D
> >>>>>>>>=0D
> >>>>>>>> Peter Shute=0D
> >>>>>>>>=0D
> >>>>>>>> ________________________________=0D
> >>>>>>>> From: <naturerecordists%4=
Message: 0yahoogroups.
Subject: com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com>=0D
> >>>>>>>> <naturerecordists=
%40yahoogroups.com><naturerecordist=0D
> >>>>>>>> s=0D
> >>>>>>>> %40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com>] On Behalf Of hartogj=0D
> >>>>>>>> Sent: Tuesday, 28 February 2012 7:19 AM=0D
> >>>>>>>> To: <naturerecordists%40y=
ahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com>=0D
> >>>>>>>> Subject: [Nature Recordists] Re: Foam for SASS=0D
> >>>>>>>>=0D
> >>>>>>>>=0D
> >>>>>>>>=0D
> >>>>>>>> Hi Peter,=0D
> >>>>>>>> The open cell foam in the nose baffle is part of the original=0D
> >>>>>>>> Crown=0D
> >>>>>>>> SASS design, and that design has proven good for natural=0D
> >>>>>>>> soundscape=0D
> >>>>>>>> recording. I think the reason for sticking with the open cell=0D
> >>>>>>>> design is mostly for the sake of consistency. Some low=0D
> >>>>>>>> frequencies=0D
> >>>>>>>> will pass through the foam nose, some frequencies are absorbed,=
=0D
> >>>>>>>> and=0D
> >>>>>>>> some will be reflected. The qualities of these transitions will=
=0D
> >>>>>>>> depend on the specific material used.=0D
> >>>>>>>>=0D
> >>>>>>>> John Hartog=0D
> >>>>>>>> rockscallop.org=0D
> >>>>>>>>=0D
> >>>>>>>> --- In=0D
> >>>>>>>> <naturerecordists%40yahoo=
groups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com><naturerecordists%=0D
> >>>>>>>> 40yahoogroups.com>, Peter Shute <pshute@> wrote:=0D
> >>>>>>>>>=0D
> >>>>>>>>> I'm building a SASS array to Rob Danielson's design (https://=
=0D
> >>>>>>>>> pantherfile.uwm.edu/type/www/audio-reports/=0D
> >>>>>>>>> BoundaryMicExperiments/=0D
> >>>>>>>>> images/PBB2N-Plans_SASS-LikeDimensionsSept2010.gif), and I=0D
> >>>>>>>>> have=0D
> >>>>>>>>> some questions about the foam used for the nose (baffle?)=0D
> >>>>>>>>>=0D
> >>>>>>>>> The plans say to use high-density open-celled foam, and I=0D
> >>>>>>>>> don't=0D
> >>>>>>>>> know how to identify the stuff. I rang the local supplier=0D
> >>>>>>>>> (Clark=0D
> >>>>>>>>> Rubber, which Australians would know), and they said they=0D
> >>>>>>>>> can cut=0D
> >>>>>>>>> a piece for a few dollars. But when I mentioned what it was=0D
> >>>>>>>>> for,=0D
> >>>>>>>>> they said it would be better to use acoustic foam, which=0D
> >>>>>>>>> doesn't=0D
> >>>>>>>>> cost much more.=0D
> >>>>>>>>>=0D
> >>>>>>>>> They said it's similar, but denser. It also comes in thinner=0D
> >>>>>>>>> sheets, so I'd have to glue two pieces together.=0D
> >>>>>>>>>=0D
> >>>>>>>>> Will it be better. Does it even matter?=0D
> >>>>>>>>>=0D
> >>>>>>>>> If the aim of the foam is to block sound from the other=0D
> >>>>>>>>> side, why=0D
> >>>>>>>>> open cell? Does it work better for that?=0D
> >>>>>>>>>=0D
> >>>>>>>>> Sorry if these are basic questions, I don't know anything=0D
> >>>>>>>>> about=0D
> >>>>>>>>> foams, their acoustic properties, and how this array works.=0D
> >>>>>>>>>=0D
> >>>>>>>>> Peter Shute=0D
> >>>>>>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>>=0D
> >>>>=0D
> >>>>=0D
> >>>>=0D
> >>>>=0D
> >>>> ------------------------------------=0D
> >>>>=0D
> >>>> "While a picture is worth a thousand words, a=0D
> >>>> sound is worth a thousand pictures." R. Murray Schafer via Bernie=0D
> >>>> Krause.=0D
> >>>>=0D
> >>>> Yahoo! Groups Links=0D
> >>>>=0D
> >>>>=0D
> >>>>=0D
> >>>=0D
> >>=0D
> >=0D
> >=0D
> >=0D
> >=0D
> > ------------------------------------=0D
> >=0D
> > "While a picture is worth a thousand words, a=0D
> > sound is worth a thousand pictures." R. Murray Schafer via Bernie=0D
> > Krause.=0D
> >=0D
> > Yahoo! Groups Links=0D
> >=0D
> >=0D
> >=0D
>=0D
=0D
=0D
=0D
|